The objective of this research is to elucidate the sequence of events which occurs when one cellular type is accepted or rejected by cells of a different cell type. The differences between normal and cancer cells in this respect will be investigated. Specifically, this specificity of interaction of cells will be investigated by studying the following areas: The interaction of cells from normal and tumor sources with aggregates and fragments of normal and tumor tissue; the effect of inhibitors of a wide range of cell metabolic processes on these specific interactions; and the development of a computational model to analyze the behavior of cells during aggregation and sorting in stationary and rotation mediated cultures with relation to their motility and adhesivity.